Mounting
Every shape shares the same two mounting holes, stacked one above the other — real arborist guidance: a tree grows in girth, not height, so two vertically-stacked points keep a constant spacing for decades, while side-by-side points would drift apart as the trunk thickens. Both holes are sized to pass a small aluminum trail nail or a paracord/zip-tie loop, so you pick the mounting method at install time — nail it straight to a tree, hang it from a branch with no permanent damage, or screw it to a free-standing post.
Material
This one lives outdoors. We'd recommend PETG over PLA — real UV and weather resistance matters here in a way it doesn't for anything else in the shop.